Water Rocket Forum

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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

The first project is very simple and also very popular. It's a airflap parachute deploy. (Without tommy timer_I will not present the tommy timer parachute deploy because I have one already). It's a mechanism that deploy the chute when the rocket lifts off.

The second project is the most popular and simple. It's called the NOAA parachute deployment system. It's a system that deploy the parachute after the apogee.

The third project is almost like the previous. It's a NOAA deployment system with a ballon. The ballon helps the nosecone to jump of the rocket.

The fourth project it's a NOAA system too. It's a bit different because the nosecone is a tennis ball inserted in a toilet paper roll (the parachute is inside the roll and it's attached to the tennis ball_ and the ball is attached to the rocket).

The fifth project is the most complicated of all. It's a baking soda and vinegar reaction chute deployment. The compressed air of the chemical reaction extends a serynge and realease the parachute. It's basead on the AntiGravity Corporation World Record Pop Bottle Rocket.

Please, give me your opinion and ideas and post comments.

Greetings,
PTrockets

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1. Is the catch a flap, held down by air pressure until the rocket slows down enough near apogee or does it immediately start deploying after launch?

2. Depends on the rocket not entering a ballistic trajectory. I have not had good luck with this but I've never made a precision collar so that may make the difference.

3. With the balloon, you have to hold down the cap until the pressure bottle expands enough to hold it in place? I like this one but I suspect getting the balloons the right size will require lots of balloons or making a size guide once you get it dialed in. Hmm where to find all that compressed air... I'm going to try this for Scouts WRD sine the required extra materials list is so short. I suspect it will require specific brands of bottles to work without getting into heat shrinking, maybe a Pepsi cap on a Coke or DrPepper bottle or such.

4. As I learned the hard way, cardboard does not like to get wet. Epoxy impregnated cardboard though... I think this one, in my non-expert opinion, the largest separation force is going to come from the ball not wanting to decelerate as fast as the rocket near apogee. If the rocket arcs over the ball may not fall with enough differential force to pull the chute out. I wonder if a streamer roll would work here.

5. Instead of vinegar, mentos and diet coke?, water and alka-seltzer? Otherwise that rocket's gonna get known as Stinky Pete. Added thoughts, I'd make the piston just a sealed piece of pipe with an o-ring. If you use a thin rod, that might allow the cylinder to tilt and seize or lose pressure. One more thought, the simulators say the rocket will experience about 2.5 g deceleration during the coast phase, so I suspect the mixing would occur before the rocket turns upside down. I'm going to try this one and just drill holes about 1" down from the top and criss-cross wires inside it to create a sieve. Then I can just pour, drop in a tablet and put on the cap.

Thank you, seriously! Your criticisms are very good!
But I'll build the rockets the way I showed you, and only then (if a failure happens), I will follow your ideas.
1-It's true that this system is not very good because the parachute deploy before the rocket hit the apogee. But I'll make a 'cup' where the parachute is 'resting'. So it will not move.
2-Yes, the collar makes all the difference because it doesn't leave the nosecone turn or 'hold' on the rocket.
3-Balloon acts as a springboard. This rocket is equal to the second but has no collar because it don't need. The balloon replaces the collar and forces the nosecone to jump.
4 - I think I'll replace the paper roll with a pvc pipe. The ball can not be attached to the rocket. I think this system is the best and simplest.
5-This is the most difficult, as I said. Mentos and coke don't work (I've tried) because the coke loses gases. Alka-Seltzer and water is a good idea and I had already thought on that, because it don't need the napkin and alka-seltzer is easier to stick on the cap. I heard that vinegar at high temperatures increases the reaction with baking soda. I'll try!
Once again, thank you!

Sorry had a paragraph at the begining that got lost saying hello and that I too was experimenting with a bunch of different ideas, to find the one or two that work really well.

As for me, I have two partially failed ideas today that I'm hoping I can salvage with a change in materials. A third is still in progress, a fourth, fifth and sixth are waiting on materials to come in. :-)

Good luck, let us know what works and what doesn't. It's great to build a body of knowledge on systems that work as well as the ones that don't.

Nice work on the pictures. Good luck with your devices. I also would like to try some of those. I am currently only using tomy timer method. Did you ever launch the rocket with the little red ball? That had a tomy timer right? How did it work for you?

Asupremeflight wrote:Nice work on the pictures. Good luck with your devices. I also would like to try some of those. I am currently only using tomy timer method. Did you ever launch the rocket with the little red ball? That had a tomy timer right? How did it work for you?

Hello Asupremeflight,
The little red ball? Do you refer to the red object in the nosecone tip? That's clay. The clay is used to give some weight to the nosecone tip. This way the rocket fly straight and turn after the agogee. I didn't use clay in my tommy timer system, but I used a beach tennis ball. I already used clay on a rocket and it works very well.
I hope I have answered to your question.

bugwubber wrote:Sorry had a paragraph at the begining that got lost saying hello and that I too was experimenting with a bunch of different ideas, to find the one or two that work really well.

As for me, I have two partially failed ideas today that I'm hoping I can salvage with a change in materials. A third is still in progress, a fourth, fifth and sixth are waiting on materials to come in. :-)

Good luck, let us know what works and what doesn't. It's great to build a body of knowledge on systems that work as well as the ones that don't.

Bugwubber

Hello Bugwubber,
I have news. I tested the vinegar and baking soda prototype system and it resulted. The syringe expanded almost immediately.
I hope I helped,

PTrockets wrote:
1-It's true that this system is not very good because the parachute deploy before the rocket hit the apogee. But I'll make a 'cup' where the parachute is 'resting'. So it will not move.

PTrockets

PTrockets, I think you might be misinterpreting someone's explanation of an airspeed flap. In general, there is a big flap against the side of the rocket. While travelling quickly through the air, the air pressure keeps this flap against the rocket. It only releases when the rocket slows down significantly, near apogee. While the rocket is on the launcher, you need some other method to hold the main flap down. Various methods have been used. The method you seem to be depicting is the use of a second, smaller, flap. At launch, this flap flips down immediately, but the big flap is still held against the rocket by air pressure, and doesn't release until the rocket slows down.

I've never made a system like this myself, but numerous people have had success. The big advanatage of this system over the other ones you show is that it relies on air speed, which actaully changes throughout the flight. Anything that relies on the rocket "flipping" at apogee is very tricky, because when the rocket is near apogee it's downward acceleration "cancels" the force of gravity, so the rocket can't really tell where down is, or when it flips. That said, there are people who have made such systems "work", they just aren't really detecting apogee, and are more prone to failure. Good luck with your experimenting.

bugwubber wrote:Sorry had a paragraph at the begining that got lost saying hello and that I too was experimenting with a bunch of different ideas, to find the one or two that work really well.

As for me, I have two partially failed ideas today that I'm hoping I can salvage with a change in materials. A third is still in progress, a fourth, fifth and sixth are waiting on materials to come in. :-)

Good luck, let us know what works and what doesn't. It's great to build a body of knowledge on systems that work as well as the ones that don't.

Bugwubber

Hello Bugwubber,
I have news. I tested the vinegar and baking soda prototype system and it resulted. The syringe expanded almost immediately.
I hope I helped,

PTrockets

That's great! Gotta love science! Does the syringe stay together when it deploys or does the top come off completely?

That's great! Gotta love science! Does the syringe stay together when it deploys or does the top come off completely?

The nosecone doesn't need to came off completely. The parachute is being pulled by a rubber band attached to the bottom of the rocket. The nosecone just up a bit and parachute jumps off.
The prototype is now trash-Now I'm building the real one.

Asupremeflight wrote:Was that ball in your tomy timer rocket not red? Did you launch it?

You're confusing me.
The color does not matter ... And it's not a ball, it's clay, as I said.
And I've launched a rocket with clay (the 'little red ball') and it worked, as I said.
I hope I have answered to your question.

PTrockets, I think you might be misinterpreting someone's explanation of an airspeed flap. In general, there is a big flap against the side of the rocket. While travelling quickly through the air, the air pressure keeps this flap against the rocket. It only releases when the rocket slows down significantly, near apogee. While the rocket is on the launcher, you need some other method to hold the main flap down. Various methods have been used. The method you seem to be depicting is the use of a second, smaller, flap. At launch, this flap flips down immediately, but the big flap is still held against the rocket by air pressure, and doesn't release until the rocket slows down.

I've never made a system like this myself, but numerous people have had success. The big advanatage of this system over the other ones you show is that it relies on air speed, which actaully changes throughout the flight. Anything that relies on the rocket "flipping" at apogee is very tricky, because when the rocket is near apogee it's downward acceleration "cancels" the force of gravity, so the rocket can't really tell where down is, or when it flips. That said, there are people who have made such systems "work", they just aren't really detecting apogee, and are more prone to failure. Good luck with your experimenting.

Alex

Hi Alex,
Two flaps? I don't understand!
This parachute system isn't good because the parachute deploys when the rocket takes off, as I said. I think you didn't realize.
Please Watch this video: My parachute system will be similar to this one.
I hope to have answered.
Greetings,

^^Yes, two flaps. At launch, one is horizontal and one is vertical. The horizontal one gets pushed down and "releases" the vertical one. The vertical doesn't move at launch, however, because the air pressure keeps it against the rocket body until the rocket slows down. That's in the description of the video at the link you gave. In the video it does release right away, but that's because there is no wind keeping the big flap down. There wouldn't be much point if it just released at launch.

SaskAlex wrote:^^Yes, two flaps. At launch, one is horizontal and one is vertical. The horizontal one gets pushed down and "releases" the vertical one. The vertical doesn't move at launch, however, because the air pressure keeps it against the rocket body until the rocket slows down. That's in the description of the video at the link you gave. In the video it does release right away, but that's because there is no wind keeping the big flap down. There wouldn't be much point if it just released at launch.